1. Field
The following description relates to detecting whether a light emitting diode (LED) array is open, and more particularly, to a detecting circuit configured to detect whether an LED array is open and an LED driver method and apparatus using the same.
2. Description of the Related Art
A liquid crystal display (LCD) is widely used because it is thin and light in weight when compared to other displays and requires a low driving voltage and low power consumption. However, because the LCD is a non-emissive element that cannot emit light by itself, it requires a separate backlight source to supply light to an LCD panel.
As a backlight source for the LCD, a cold cathode fluorescent lamp (CCFL) and a light emitting diode (LED) are mostly used. The CCFL, however, may cause environmental pollution because it uses mercury. Also, the CCFL includes slow response time and low color reproducibility and is not helpful for the LCD panel to be light in weight, thin, short, and small.
On the other hand, the LED is eco-friendly because it does not use environmentally harmful materials and is capable of achieving impulse driving. Also, the LED has good color reproducibility and can change brightness or color temperature arbitrarily by adjusting an amount of light emitted from red, green, and blue light emitting diodes. The LED has further advantages suitable for a light, thin, short, and small configuration for the LCD panel. Thus, in recent years, the LED has been frequently used as a backlight source for the LCD panel.
LED arrays include a plurality of LEDs and are operatively connected to one another. When LED arrays are used in the LCD backlight unit, a driving circuit is needed to provide a constant current to each of the LED arrays, and a dimming circuit is also needed to adjust brightness and color temperature arbitrarily or compensating for overheating.
An electrical shock may disconnect the LED arrays from an LED driver by opening one or more of the connections in the LED arrays. In this case, a protection circuit to detect the opening of the LED array is needed.
However, the protection circuit may connect a diode to an end of the LED array and detect whether the LED array is open or not depending on whether the diode conducts electricity or not. However, such protection circuit may wrongfully detect that the LED array is open when an abnormal feedback voltage occurs due to initial driving or a peak current of a constant current.